1. Field
Apparatuses and methods consistent with exemplary embodiments relate to dual coupler devices configured to receive lights of different polarization components, spectrometers including the dual coupler devices, and non-invasive biometric sensors including the spectrometers.
2. Description of the Related Art
A non-invasive blood sugar measurement may be performed through spectroscopic analysis of a biometric signal that is obtained when incident light is reflected off the skin of a human subject. With improvements in performance of mobile apparatuses such as mobile phones, integrating a non-invasive biometric sensor into a mobile apparatus may be attempted. To this end, a micro spectrometer may be installed in a mobile apparatus.
For example, the micro spectrometer may be implemented as a linear variable filter (LVF)-based spectrometer or a filter array-based spectrometer. The LVF-based spectrometer may have a structure in which a spacer having a gradually changing thickness is disposed on a plurality of photodiode pixels so that the thickness of the LVF-based spectrometer varies continuously or in steps. Respective photodiode pixels in the LVF-based spectrometer may sense lights of different wavelength bands because a transmission wavelength varies depending on the thickness of the spacer. The filter array-based spectrometer may have a structure in which band-pass filters (BPFs) of different transmission bands are disposed in respective photodiode pixels.